The invention relates to novel microorganisms which are capable, at high specific activities, of converting D- or L- or D,L-5-monosubstituted hydantoins or D- or L- or D,L-N-carbamoyl-.alpha.-amino acids into the corresponding, enantiomerically pure L-.alpha.-amino acids.
Up to the present, numerous methods have been described in the art concerning the fermentative or enzymatic transformation of N-5-monosubstituted hydantoins into the enantiomerically pure L-.alpha.-amino acid (see Syldatk, et al., "Microbial and Enzymatic Production of L-Amino Acids from D,L-5-Monosubstituted Hydantoins," Biocatalytic Production of Amino Acids and Derivative, Rozzell, J. D. and Wagner, F., eds., Hanser Verlag, Munich, 1992, pp. 129-176; Yokozeki, et al., (1986), "Optimal Conditions for the Enzymatic Production of L-Aromatic Amino Acids from the Corresponding 5-Substituted Hydantoins," Agric. Biol. Chem. 51: 729-736; and Yokozeki, et al., (1986), "Mechanism of Asymmetric Production of L-Aromatic Amino Acids from the Corresponding Hydantoins by Flavobacterium Sp.," Agric. Biol. Chem., 51: 737-746). For instance, this latter reference describes a reaction mechanism for the hydrolysis of 5-arylalkyl hydantoins using the example of 5-benzyl hydantoin with a cleaned-up hydantoinase of Flavobacterium sp. AJ-3912. The relative rates of the forward and of the reverse reactions were determined thereby and it was shown that the forward reaction of D-5-benzyl hydantoin to N-carbamoyl-D-phenyl alanine took place distinctly more slowly than the hydrolysis of L-5-benzyl hydantoin to N-carbamoyl-L-phenyl alanine. No mention was made of the mechanism of the enantioselective hydrolysis of 5-alkyl hydantoins since D,L-5-methyl thioethyl hydantoin was only able to be converted to N-carbamoyl-L-methionine in trace amounts.